Dynamically balanced molded blade assemblies for blowers and fans

ABSTRACT

Dynamically balanced molded blade assemblies may be formed. A face plate of a dynamically balanced molded blade assembly may have one or more openings and/or one or more protrusions so that the blade assembly is within acceptable balance tolerance when rotated by a motor shaft of a fluid moving device.

BACKGROUND

1. Field of the Invention

The present invention relates to fluid moving devices such as blowers, fans, and propellers. More particularly, the invention relates to providing openings in face plates of molded blade assemblies of the fluid moving devices so that the blade assemblies are dynamically in balance when rotated by the motor of the fluid moving devices during use.

2. Description of Related Art

Fluid moving devices may be used to move fluid in a desired direction. For example, fluid moving devices may be used to move air in air conditioning system to move air from air inlets, past one or more heat exchangers, and through air vents. Fluid moving devices include blowers and fans. The blade assemblies of the fluid moving devices move the gas. The blower wheels of blowers and fan blades of fans are blade assemblies. Blade assemblies typically include a plurality of blades around a circular face plate. A shaft of a motor may be coupled to a hub of the face plate. The motor turns the shaft and the blade assemblies create desired flow (e.g., air flow). Having balanced blade assemblies may inhibit vibrations, noise, and wear on bearings and other parts of the motor. Blade assemblies may be made of polymeric materials so the blade assemblies are light, easy to produce, and relatively inexpensive. Blade assemblies may be made using injection molding processes or other formation processes.

One way to make balanced blade assemblies is to subject the blade assembly to a balancing process after the blade assembly is produced. For example, the blade assembly may be coupled to a balancing machine and spun to determine where to apply one or more exterior balancing clip-on weights. A weight or weights are added on the light side of the blade assembly to counter the weight of the heavier side. Some blade assemblies are formed with excess material at select locations. Some of the excess material may be cut or otherwise removed from the heavier side to bring the blade assembly into balance when the blade assembly is rotated.

U.S. Pat. No. 7,063,507 to Hsieh, which is incorporated herein by reference, describes a process of forming a balance adjusted fan by inserting balance weights in openings in the hub of the blade assembly. U.S. Pat. No. 5,547,365 to Chuang, which is incorporated herein by reference, describes a method of balancing a fan blades with an integrally formed shaft by shifting the position of a reference line used when coupling a magnetic ring to the blade assembly and/or by adjusting the length of one or more knock out pins to change the depth of dents made in the blade assembly by the knock out pins when the blade assembly is ejected from the mold. The mold includes a knock out pin for each blade of the blade assembly. U.S. Pat. No. 5,927,947 to Botros, which is incorporated herein by reference, describes a balanced blower wheel that is made by a mold with an adjustable portion that controls the thickness of a portion of the inlet ring of the blade assembly. The thickness of the portion of the inlet ring is controlled to produce balanced blade assemblies.

Other methods to produce balanced blade assemblies may also be used. Another method for producing balanced blade assemblies includes cutting selected perimeter ejector pins of the mold so that the mold produces pegs in the resulting blade assemblies that act as counter weights. Another method of producing balanced blade assemblies involves removing metal from the mold from one or more locations to increase the amount of polymer at the one or more locations. The excess polymer may be a counter weight that balances the resulting blade assembly. Another method of balancing the blower wheel during blade assembly formation involves adjusting one or more set screws that control polymer flow into the mold. The set screws are typically located at fixed positions such that the thickness of a portion of the blade assembly that changes due to adjustment of the set screw is in a vertical plane in an axial direction relative to the rotational axis of the blade assembly. Such methods may require tremendous amounts of trial and error and may require periodic testing of the blade assemblies to ensure that the produced blade assemblies are balanced.

Blade assemblies that are light weight, relatively inexpensive to produce, and balanced are needed. The blade assemblies may be components of fluid moving devices. The blade assemblies may be dynamically balanced when rotating within acceptable balance tolerance required by the industry in which the blade assemblies are used.

SUMMARY

Some embodiments described herein are related to molded blade assemblies. The blade assemblies may be components of fluid moving devices. The blade assemblies may include a plurality of blades coupled to face plates. The face plates may include hubs and balancing means. The hubs may have shaft bores that allow the blade assemblies to be coupled to motor shafts of the fluid moving devices. The balancing means dynamically balances the blade assemblies within acceptable balance tolerance when the blade assemblies are rotated by the motor shafts.

In some embodiments, the balancing means of the blade assemblies are openings formed in the face plates of the blade assemblies. The openings may be through openings and/or blind openings. If the blade assembly includes more than one opening, the openings may be symmetrically arranged about a center of the face plate. If the blade assembly includes more than one opening, at least one of the openings may have a different size than other openings. In some embodiments, the balancing means of the blade assemblies are protrusions extending from the face plate. In some embodiments, the balancing means of the blade assemblies includes openings and protrusions.

Some embodiments described herein are related to fluid moving devices. The fluid moving devices include motors with shafts. A molded blade assembly may be coupled to the shaft of the motor. The molded blade assembly may include a hub with a shaft opening, a face plate, and a plurality of blades. The face plate includes balancing means for dynamically balancing the blade assembly within acceptable balance tolerance when the blade assembly is rotated at operating speed by the shaft. The balancing means may comprise one or more openings formed in the face plate and/or one or more protrusions extending from the face plate. The fluid moving devices may be blowers, fans, or other fluid movers.

In some embodiments, methods may be used to produce dynamically balanced molded blade assemblies. The method may include forming a first blade assembly using a mold. The first blade assembly may be coupled to a test machine. The test machine may be operated to determine the balance characteristics of the first blade assembly at a working rotational speed. The results may be used to assess a location of one or more balancing means to be incorporated in a face plate of the first blade assembly to result in a dynamically balanced first blade assembly. The mold may be adjusted to form the balancing means in the face plate of a blade assembly produced by the mold. The mold may be used to from one or more dynamically balanced molded blade assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the methods and apparatus of the present invention will be more fully appreciated by reference to the following detailed description of presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings in which:

FIG. 1 depicts a perspective view of an embodiment of a blower.

FIG. 2 depicts a perspective view of an embodiment of a fan.

FIG. 3 depicts a perspective of an embodiment of a motor.

FIG. 4 depicts a perspective view of the shaft of the motor.

FIG. 5 depicts a perspective view of an embodiment of a single gas inlet blade assembly for a blower.

FIG. 6 depicts a side view of the single gas inlet blade assembly depicted in FIG. 5.

FIG. 7 depicts a perspective view of an embodiment of a double gas inlet blade assembly for a blower.

FIG. 8 depicts a side view of the double gas inlet blade assembly depicted in FIG. 7.

FIG. 9 depicts a side view of the blade assembly depicted in FIG. 2.

FIG. 10 depicts a perspective view of an embodiment of a blade assembly with a protrusion formed on the face plate of the blade assembly.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. The drawings may not be to scale. It should be understood that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but to the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION OF EMBODIMENTS

A fluid moving device may be used in a system to direct the flow of a fluid in a desired direction or directions at a desired rate. A fluid moving device may include a motor with a shaft, and a blade assembly that is coupled to the shaft of the motor. The motor rotates the shaft to rotate the blade assembly. The blade assembly moves the fluid. The fluid may be gas (e.g., air), liquid (e.g., water), a powder (e.g., flour), and/or combinations thereof. Examples of fluid moving devices that move gas are blowers and fans. Examples of fluid moving devices that move liquid and/or solids are propellers and mixers.

The blade assembly of the fluid moving device needs to be within an acceptable balance tolerance. If the blade assembly is not within the acceptable balance tolerance the fluid moving device may have too much vibration, make too much noise, and/or the life of the motor may be shortened.

Blade assemblies may be made using an injection molding process. The blade assembly may be made from a single type of polymer, or from a blend of polymers. The polymer may include one or more additives, stabilizing compounds, and/or strengthening materials (e.g., glass fibers).

A number of factors may influence the balance of the blade assembly of a fluid moving device. These factors may include: 1) the operating rotation speed of the blade assembly, 2) the size of the blade assembly, 3) the location of mass due to the location of gates in the mold used to form the blade assembly and due to flow characteristics of the mold design and process, and 4) unbalance due to the motor shaft. Many shafts of motors used to rotate blade assemblies include a flat portion or “D” profile that facilitates coupling the blade assembly to the shaft. The “D” profile allows an interference fit to be formed between the shaft and the blade assembly to inhibit slippage of the blade assembly on the shaft of the motor. In some embodiments, a fastener or fasteners secure the blade assembly to the shaft. The material removed from the shaft to form the “D” profile may contribute to unbalance of the blade assembly coupled to the shaft when the shaft rotates.

To bring or make rotating blade assemblies within acceptable balance tolerance, some material of the face plates of the blade assemblies may be removed. The face plate of the blade assembly may be an area of the blade assembly where removal of material will have the least adverse affect on the strength of the blade assembly. Molding blade assemblies with material removed from the face plates to balance the blade assemblies allows for cost savings due to less material used when the blade assembly is made and/or due to elimination of secondary balancing labor costs. In some embodiments, the openings in the face plate may be formed after the blade assembly is molded. For example, openings in the face plate may be drilled, punched, cut or otherwise formed after the blade assembly is formed. In some embodiments, one or more scoring marks may be formed in the face plate that allow material to be punched out of the face plate to make openings in the face plate after the blade assembly is formed.

The opening or openings formed in the face plate may be formed completely through the face plate or only partially through the face plate (e.g., blind openings). In some embodiments, some openings may be through openings while others are blind openings. The openings may have any desired shape, such as, but not limited to circular, arced, oval, elliptical, rectangular, polygonal and/or irregularly shaped.

If more than one opening is formed in the face plate, the openings may have different sizes. Having various sized openings spaced around the face plate may provide a relatively simple way to compensate for the missing or removed material mass in the “D” profile of motor shaft. In some embodiments, the openings may be spaced in a regular angular pattern around the face plate. For example, six openings may be formed in the face plate around the face plate with the center of each opening being at about a 60° angle relative to the center of the next opening and relative to the center of the face plate. In some embodiments, the openings may be angularly spaced in an irregular pattern.

In some embodiments, the radial distance to the center of the openings from a center of the face plate is substantially the same for all of the openings in the face plate. In other embodiments, the distance from the center of the face plate to the center of one or more of the openings in the face plate may be different than the radial distance from the center of the face plate to the center of another opening in the face plate. In some embodiments, two or more sets of openings may be formed at different radial distances from the center of the face plate. For example, a first set of three circular openings may be formed at a radial distance of about 1 inch from the center of the face plate, the three openings being spaced 120° apart. A second set of four arced openings may be formed at a radial distance of about 1.5 inches from the center of the face plate, the four openings being spaced 90° apart from each other.

In some embodiments, the position of the opening or the openings in the face plate may be influenced by the size of the blade assembly and/or by the rotation speed of the blade assembly. The radial distance of the opening or openings from the center of the face plate may increase as the size of the blade assembly and/or the operating speed of the blade assembly increases.

FIG. 1 and FIG. 2 depict embodiments of fluid moving devices 50. FIG. 1 depicts an embodiment where fluid moving device 50 is a blower. Fluid moving device 50 may include housing 52, motor 54, and blade assembly 56. Fasteners known and commonly used in the art may be used to hold sections of housing 52 together and to secure motor 54 to the housing. If the fluid moving device is a blower, the blade assembly is a blower wheel. In some embodiments, a shaft may exit each end of the motor. A blade assembly may be coupled to each shaft to form a dual blower wheel blower.

FIG. 2 depicts an embodiment where fluid moving device 50 is a fan. Fluid moving device 50 may include motor 54, and blade assembly 56. In some embodiments, blade assembly 56 and/or motor 54 may be placed in a frame or cage. If the fluid moving device is a fan, the blade assembly is the fan blade.

FIG. 3 depicts an embodiment of motor 54 that may be used to rotate the blade assembly of a fluid moving device. Motor 54 may include body 60 and shaft 62. Motor 54 may be electrically coupled to a power source. The power source provides electricity to motor 54 to rotate shaft 62. FIG. 4 depicts a detail representation of shaft 62. Shaft 62 may include flat 64. Flat 64 facilitates coupling of the blade assembly to the motor.

FIGS. 5-8 depict embodiments of blade assemblies 56 for blowers. As known in the art, a blade assembly may have a forward incline blade design or a backward incline blade design. FIG. 2 and FIG. 9 depict an embodiment of blade assembly 56 for a fan. Blade assemblies 56 may include blades 66 and face plate 68. Face plate 68 may include hub 70, ribs 72, and one or more openings 74. In some embodiments, rims 76 support the ends of blades 66. Hub 70 may be used to couple blade assembly 56 to the motor shaft. Hub 70 may include a shaft bore. Ribs 72 may add rigidity to face plate 68 and strengthen blade assembly 56. Opening or openings 74 may reduce the weight of blade assembly 56 in one or more locations so that the blade assembly is balanced within acceptable tolerance when mounted to the shaft of the motor and rotated.

FIG. 5 and FIG. 6 depict an embodiment of blade assembly 56 for a single gas inlet blower. FIG. 1 depicts blade assembly 56 used to form the single gas inlet blower with a forward incline blade design. Gas enters fluid moving device 50 through inlet 78 and exits the fluid moving device through outlet 80. As shown in FIG. 5 and FIG. 6, openings 74 may be formed in face plate 68. Openings 74 may balance blade assembly 56 so that the blade assembly is balanced within acceptable tolerance when rotated by the motor of the fluid moving device. Opening 74′ may be smaller than other openings 74.

FIG. 7 and FIG. 8 depict an embodiment of blade assembly 56 for a double gas inlet blower. When blade assembly 56 is coupled to the shaft of the motor of the fluid moving device, the housing of the fluid moving device has two inlets to allow gas to be drawn into the blade assembly on each side of face plate 68. Openings 74 may be formed in face plate 68 so that blade assembly is balanced within acceptable tolerance when rotated by the motor of the fluid moving device. Openings 74″ may be blind openings that do not extend through face plate 68. One or more openings may be smaller than other openings.

FIG. 9 depicts an embodiment of blade assembly 56 of a fan. FIG. 2 depicts blade assembly 56 coupled to shaft 62 of motor 54. Openings may be formed in face plate 68. One or more of the openings may be blind openings. Opening size and depth may depend on strength considerations and balance considerations so that the blade assembly is balanced within acceptable tolerance on a rotating motor shaft.

In some embodiments, the blade assembly may be formed with one or more protrusions from the face plate that add weight to the blade assembly so that the blade assembly is dynamically balanced when rotating. The protrusions may have any desired shape, such as, but not limited to, block shaped, cylindrical, domed, or irregularly shaped. In some embodiments, only protrusions are used to produce dynamically balanced blade assemblies. Different sizes and/or different protrusion lengths may be formed on the face plate of the blade assembly. In some embodiments, protrusions are used in conjunction with openings to produce dynamically balanced blade assemblies. FIG. 10 depicts an example of blade assembly 56 that includes protrusion 82 and openings 74 in face plate 68. Protrusion 82 may be formed as part of face plate 68 near a flat portion of hub 70. Protrusion 82 may add extra weight to blade assembly 56 to counteract missing weight mass of the shaft due to the flat portion formed in the shaft (i.e., flat 64 depicted in FIG. 4).

A mold may be formed to make the blade assembly without openings formed in the face plate of the blade assembly. One or more blade assemblies may be molded using the mold to form blade assemblies without openings in the face plate. At least one of the blade assemblies may be coupled to a balancing device. The balancing device may have a motor shaft that is substantially the same as the motor shafts to which the balanced blade assemblies formed by the mold are to be coupled. The blade assembly without openings in the face plate may be coupled to the shaft of the balancing device in the same manner that the balanced blade assemblies are to be coupled to the motor shafts. The balancing device may be activated to rotate the shaft to the same operating speed at which the shafts of the motors will run. The balancing device may be used to determine where the blade assembly without openings is out of balance at the operating test speed.

Rotation may be stopped. Based on information provided from the balancing device, one or more openings may be formed in the face plate of the blade assembly so that the blade assembly will come within acceptable balanced tolerances. In some embodiments, one or more weights are attached to the face plate or to one or more blades. The blade assembly may be rotated on the balancing device to the operating test speed to determine if the blade assembly is in balance within acceptable tolerance. If the blade assembly is not in balance, additional openings in the face plate may be formed or existing openings in the face plate may be enlarged so that the blade assembly is in balance when rotated at the operating speed. If an error is made and too much material from the face plate is removed, the process can be restarted with a new blade assembly that has no openings formed in the face place. If the blade assembly is balanced within acceptable tolerances, the mold may be adjusted. The adjusted mold may include obstructions placed in portions of the mold so that blade assemblies formed by the mold include openings in the face plate at desired locations and/or openings may be formed in the mold so that blade assemblies formed by the mold include protrusions extending from the face plate at desired locations.

One or more blade assemblies may be made with the adjusted mold. One or more of the blade assemblies made from the adjusted mold may be tested on the balance device to ensure that blade assemblies made using the mold are within acceptable balance tolerance. If needed, the mold may be further adjusted to produce blade assemblies that are within acceptable balance tolerance when rotated on a motor shaft.

Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims. 

1. A molded blade assembly, comprising: a plurality of blades; a face plate coupled to the plurality of blades, wherein the face plate comprises: a hub with a shaft bore configured to couple the blade assembly to a shaft of a motor; and balancing means configured to dynamically balance the blade assembly within acceptable balance tolerance when the blade assembly is rotated by the shaft of the motor during use.
 2. The molded blade assembly of claim 1, wherein the balancing means comprises one or more openings formed in the face plate.
 3. The molded blade assembly of claim 1, wherein the balancing means comprises a plurality of openings formed in the face plate, and wherein at least one of the openings comprises an opening completely through the face plate.
 4. The molded blade assembly of claim 1, wherein the balancing means comprises a plurality of openings formed in the face plate, and wherein the openings are evenly spaced angularly about a center of the face plate or irregularly spaced angularly about the center of the face plate.
 5. The molded blade assembly of claim 1, wherein the balancing means comprises a plurality of openings formed in the face plate, and wherein at least one of the openings has a different size than at least one other opening.
 6. The molded blade assembly of claim 1, wherein the balancing means comprises at least one blind opening formed in the face plate.
 7. The molded blade assembly of claim 1, wherein the balancing means comprises one or more protrusions extending from the face plate.
 8. The molded blade assembly of claim 1, wherein the balancing means comprises at least one protrusion extending from the face plate, and at least one opening formed in the face plate.
 9. A fluid moving device, comprising: a motor having a shaft; a molded blade assembly coupled to the shaft, wherein the blade assembly comprises a hub with a shaft opening, a face plate, and a plurality of blades; and wherein the face plate includes balancing means for dynamically balancing the blade assembly within acceptable balance tolerance when the blade assembly is rotated at operating speed by the shaft.
 10. The fluid moving device of claim 9, wherein the fluid moving device is a blower.
 11. The fluid moving device of claim 9, wherein the fluid moving device is a fan.
 12. The fluid moving device of claim 9, wherein the balancing means comprises one or more openings formed in the face plate.
 13. The fluid moving device of claim 9, wherein the balancing means comprises a plurality of openings formed in the face plate, and wherein at least one of the openings comprises an opening completely through the face plate.
 14. The fluid moving device of claim 9, wherein the balancing means comprises a plurality of openings formed in the face plate, and wherein the openings are evenly spaced angularly about a center of the face plate or irregularly spaced angularly about the center of the face plate.
 15. The fluid moving device of claim 9, wherein the balancing means comprises a plurality of openings formed in the face plate, and wherein at least one of the openings has a different size than at least one other opening.
 16. The fluid moving device of claim 9, wherein the balancing means comprises at least one blind opening formed in the face plate.
 17. The fluid moving device of claim 9, wherein the balancing means comprises one or more protrusions extending from the face plate.
 18. The fluid moving device of claim 9, wherein the balancing means comprises at least one protrusion extending from the face plate, and at least one opening formed in the face plate.
 19. A method of producing dynamically balanced molded blade assemblies, comprising: forming a first blade assembly using a mold; coupling the first blade assembly to a test machine; operating the test machine to determine the balance characteristics of the first blade assembly at a working rotational speed; assessing a location of one or more balancing means to be incorporated in a face plate of the first blade assembly to result in a dynamically balanced first blade assembly; and adjusting the mold to form the balancing means in the face plate of a blade assembly produced by the mold; and using the mold to form one or more dynamically balanced blade assemblies.
 20. The method of claim 19, wherein the balancing means comprises at least one opening formed in a face plate of a blade assembly produced by the mold.
 21. The method of claim 19, wherein the balancing means comprises at least one protrusion formed as part of the face plate of a blade assembly produced by the mold. 